# QED
## English
### Pronunciation

* (Received Pronunciation) IPA: /ˌkjuːiːˈdiː/
* Audio (Received Pronunciation):(file)
* (General American) IPA: /ˌkjuˌiˈdi/

### Etymology 1

From q(uantum) e(lectro)d(ynamics).

#### Noun

QED (uncountable)
* (physics) (Partial) initialism of quantum electrodynamics.
** 1980 January, W. B. Atwood, “Lepton Nucleon Scattering”, in Ann Mosher, editor, Proceedings of Summer Institute on Particle Physics: July 9–20, 1979: Quantum Chromodynamics (SLAC Report), Springfield, Va.: National Technical Information Service, U.S. Department of Commerce, →OCLC, part I (Lectures), section 3.1 (The General Scheme), page 26, column 1:QCD is a theory of quark interactions much analogous to QED: the interaction is carried by "gluons" (analogous to photons) which couple to the "color" (analogous to charge) of the quarks.
** 2006, A[nthony] Zee, “Introduction to the 2006 Edition”, in Richard P[hillips] Feynman, QED: The Strange Theory of Light and Matter (Princeton Science Library), Princeton, N.J., Woodstock, Oxfordshire: Princeton University Press, →ISBN, page xii:By the way, these days QED is considered a relatively simple example of a quantum field theory.
** 2011, Brian Cox, Jeff Forshaw, “Interaction”, in The Quantum Universe: Everything that Can Happen Does Happen, London: Allen Lane, →ISBN, page 176:QED is the theory that explains how electrically charged particles, like electrons, interact with each other and with particles of light (photons). […] Pretty much everything else – certainly everything you see and feel around you – is explained at the deepest known level by QED. Matter, light, electricity and magnetism – it is all QED.
** 2015, Abdus Salam, “Quantum Electrodynamics”, in David L. Andrews, editor, Photonics: Scientific Foundations, Technology and Applications: Fundamentals of Photonics and Physics, volume I, Hoboken, N.J.: John Wiley & Sons, →ISBN, section 8.10 (Resonance Energy Transfer), page 271:Finally, there is still plenty of room to employ and apply QED theory for predictive purposes, by proposing new phenomena, especially within the realm of photonics, thereby ensuring QED remains relevant to current and future generations of researchers working in chemical physics.
** 2018, James Everitt, “The Aim and Approach”, in A Wave Theory of Universal Resonance: The Physical Basis of Quantum Electro-dynamics in the Cohesive Mechanics of a Unitary Universal Field, volume 1, [Munich, Bavaria]: GRIN Verlag, →ISBN, page 12:The aim of this work is essentially twofold: to establish the conception and thus model of a 'unitary universal cohesive field' from 'first principles' within which existing theories, primarily QED and the foundation of its approach, may be understood both in principle and therefore from any abstruse mathematical perspective extrapolated from it; […]
** 2020 February 28, George Johnson, “Freeman Dyson, Math Genius Turned Technological Visionary, Dies at 96”, in The New York Times‎, →ISSN:Although his own early work on QED helped bring photons and electrons into a consistent framework, Dr. Dyson doubted that superstrings, or anything else, would lead to a Theory of Everything, unifying all of physics with a succinct formulation inscribable on a T-shirt.

##### Derived terms

* cavity QED
* qQED (“quenched quantum electrodynamics”)

##### Related terms

* QCD (“(partial) initialism of quantum chromodynamics”)

### Etymology 2

See Q.E.D.

#### Phrase

QED
* Alternative form of Q.E.D.; Initialism of quod erat demonstrandum.
** 1684 August 30, Mr. Ash, “A New and Easy Way of Demonstrating Some Propositions in Euclid”, in Philosophical Transactions: Giving Some Accompt of the Present Undertakings, Studies and Labours of the Ingenious in Many Considerable Parts of the World, volume XIV, number 162, London: Printed by T. R. for John Martyn, printer to the Royal Society; […] , →OCLC, page 674:[A]fter the ſame manner S and U are proved to be equal, therefore the ſquare of CB is equal to the ſquare of the 2 other ſides QED.

### References

* ↑ “QED, n.$^2$”, in OED Online ⁠, Oxford: Oxford University Press, December 2007; “QED, abbrev.”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.

### Further reading

* quantum electrodynamics on Wikipedia.Wikipedia
* Q.E.D. on Wikipedia.Wikipedia

### Anagrams

* DEQ

## Latin
### Phrase

QED
* QED (“quod erat demonstrandum”) Initialism of quod erat demonstrandum.

#### Descendants

* English: QED (“quod erat demonstrandum”)

## Portuguese
### Etymology

Borrowed from Latin QED.

### Phrase

QED
* (sciences) QED
    Synonym: CQD